station_id string | date date32 | precip_mm float64 | precip_nophen int8 | precip_quality int8 | precip_homog int8 | max1h_mm float64 | max1h_nophen int8 | max1h_quality int8 | max1h_homog int8 | max10m_mm float64 | max10m_nophen int8 | max10m_quality int8 | max10m_homog int8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
a0365 | 1974-01-01 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-02 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-03 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-04 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-05 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-06 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-07 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-08 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-09 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-10 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-11 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-12 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-13 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-14 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-15 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-16 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-17 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-18 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-19 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-20 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-21 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-22 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-23 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-24 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-25 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-26 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-27 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-28 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-29 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-30 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-01-31 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-01 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-02 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-03 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-04 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-05 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-06 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-07 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-08 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-09 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-10 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-11 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-12 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-13 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-14 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-15 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-16 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-17 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-18 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-19 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-20 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-21 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-22 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-23 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-24 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-25 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-26 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-27 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-02-28 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-01 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-02 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-03 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-04 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-05 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-06 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-07 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-08 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-09 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-10 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-11 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-12 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-13 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-14 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-15 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-16 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-17 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-18 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-19 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-20 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-21 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-22 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-23 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-24 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-25 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-26 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-27 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-28 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-29 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-30 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-03-31 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-01 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-02 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-03 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-04 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-05 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-06 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-07 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-08 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-09 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
a0365 | 1974-04-10 | null | null | 0 | 1 | null | null | 0 | 1 | null | null | 0 | 1 |
jma-rain-tokyo
Rainfall of the 31 stations of the Japan Meteorological Agency (JMA) in Tokyo (東京都, prefecture number 44 of the JMA), 1974 to 2025, with the JMA's flags, as Parquet:
- daily: the daily total, the greatest 1 hour amount and the greatest 10 minute amount of each day, 588,783 station-days;
- hourly: the amount of each hour, 8,660,976 station-hours.
(The dataset was first published as jma-tokyo-daily-rain with the daily values only, and renamed.)
The dataset is meant to grow: later versions may add years, elements or finer time steps. Each fetch keeps
its files as served under raw/<date of the fetch>/, and the Parquet is rebuilt from the latest fetch.
Source
- The JMA's 過去の気象データ・ダウンロード (download of past weather data),
https://www.data.jma.go.jp/risk/obsdl/index.php. The page sends a form to
/risk/obsdl/show/tableand gets a CSV (Shift_JIS);scripts/fetch_daily.shsends the same form (read from the page's script,top.bundle.js, on 2026-10-26). This is not a published API and can change. - Stations: the station list of the page for prefecture 44 (
/risk/obsdl/top/station,pd=44), kept asraw/2026-10-26/stations_44.json. All 31 stations in it, including the islands and the stations that have ended. - One request per station for 1974-01-01 to 2025-12-31, elements 降水量の合計 (
["101",""]), 1時間降水量の最大 (["105","1"]) and 10分間降水量の最大 (["105","10"]), daily values (aggrgPeriod=1). Fetched 2026-10-26 between 14:59 and 15:14 JST (the time of each CSV is in its first line and inparquet/daily_files.parquet). The CSVs are kept unchanged inraw/2026-10-26/daily/. - Hourly values (
aggrgPeriod=9, element 降水量["101",""]): one request per station and year, for the years in which the station has daily values (988 requests, listed inraw/2026-10-26/hourly_plan.tsv; a request of ten years was refused with HTTP 500).scripts/fetch_hourly.shandscripts/fetch_hourly_all.sh. Fetched 2026-10-26 between 15:48 and 17:04 JST. The CSVs are kept unchanged inraw/2026-10-26/hourly/<station>/<year>.csv. - Every raw file has its sha256 in
raw/2026-10-26/MANIFEST.json.
Files
| File | Rows | What a row is |
|---|---|---|
parquet/daily.parquet |
588,783 | A station and a day (JST) |
parquet/stations.parquet |
31 | A station |
parquet/hourly.parquet |
8,660,976 | A station and an hour (JST) |
parquet/daily_files.parquet |
31 | A CSV of the fetch: station, file, the time the JMA put in it, rows |
parquet/hourly_files.parquet |
988 | The same for the hourly CSVs |
Columns of daily.parquet
station_id (s + 5 digits for a weather station 気象台, a + 4 digits for an AMeDAS station),
date (JST), then for each of precip (daily total), max1h (greatest 1 hour amount) and max10m (greatest 10
minute amount):
| Column | Meaning (from the JMA's help for the CSV) |
|---|---|
<element>_mm |
The value in mm. Null where the CSV is blank |
<element>_nophen |
現象なし情報: 1 no rain, 0 rain. Only weather stations have it; null for AMeDAS |
<element>_quality |
品質情報: 8 normal, 5 quasi-normal (some data missing, within the allowance), 4 insufficient data, 2 doubtful, 1 missing, 0 not observed |
<element>_homog |
均質番号: a change of the number marks a change of the observing environment; values with different numbers are not directly comparable. The JMA numbers them from 1 within each request |
Every station has a row for every day of the request, also before it started and after it ended; those
rows have no value. The hourly table has the hours of the years requested for each station only. stations.parquet has station_id, station_name, kind (synop or amedas),
lat and lon (decimal degrees, converted from the degrees and minutes to 0.1 minute of the list),
elevation_m, ended (the date the list gives for the end of observation) and kansoku (the list's code of
the elements a station observes; 100000 is rain only).
Columns of hourly.parquet
station_id, time_end (the end of the hour, JST, as the JMA writes it: 2019-10-12 01:00 is the hour
from 00:00 to 01:00 of 2019-10-12, and 2019-10-13 00:00 is the last hour of 2019-10-12), then
precip_mm, precip_nophen and precip_quality as above, and precip_homog_in_file: the homogeneity
number of the CSV of that station and year. As the JMA numbers from 1 in each request, it can be compared
only within a year; use the daily precip_homog across years.
The day of an hour is the date of time_end - 1 hour. With that, the 24 hours of a day add up to the
daily total of daily.parquet on 354,034 of the 354,040 days that have 24 hourly values and a daily
value; the 6 others are at weather stations of the islands in 1990 to 1994 (三宅島, 父島, 八丈島), by
0.5 to 2.0 mm. The daily greatest 1 hour amount is larger than the greatest hourly amount of the same day
on many days (it is measured over any 60 minutes, not only from the hour; this reading is not confirmed by
the JMA's text), and smaller on 4 days (Tokyo in 1976 and 1979, 南鳥島).
What was changed
- The CSVs were read with their own header rows (weather stations have four columns per element, AMeDAS
three, without 現象なし情報), values made numbers and blanks null. Nothing was dropped, filled or
corrected.
scripts/convert.pycounts that every CSV row is in the Parquet and that (station, date) and (station, time_end) are unique. In the hourly table only the homogeneity column was renamed (precip_homog_in_file). - The Parquet was checked against the CSVs with a second reader (DuckDB's CSV reader): rows, non-null values and the sum of each element agree for every station, daily and hourly. Every station and year of the hourly table has 8,760 hours, or 8,784 in a leap year.
Known issues (measured 2026-10-26)
- In the mainland only the Tokyo station (s47662) has values before 1976; the AMeDAS stations start in 1976 (府中 on 1976-12-15, 小沢 on 1977-08-02), 調布 ended on 1976-12-13.
- The 10 minute maximum of the AMeDAS stations starts in 2008 or 2009; Tokyo has it from 1974. The 1 hour maximum is there for the whole record of every station.
- A 0 of a weather station is either no rain (
nophen1, 39,169 days) or rain that came to 0.0 mm (nophen0, 29,679 days). An AMeDAS 0 cannot be told apart. - 練馬 (a1002) changes homogeneity number on 2012-12-26. The homogeneity number of Tokyo stays 1 from 1974 to 2025. The station list gives the present position only; past positions are not in the data.
- 三宅島 (s47677) has 410 missing days in 2000 to 2005.
- In the hourly table, 1,199 station-days have between 1 and 23 hourly values, and 183 have 24 hourly values while the daily total is null. 練馬's homogeneity number changes at 2012-12-26 01:00 in the hourly CSV of 2012, as in the daily one.
- Two names are used by two stations each: 新島 (a1134 ended 2008, a1522) and 神津島 (a1505 ended 2006,
a1523). Use
station_id. - The JMA can correct past values. A later fetch of the same request is not guaranteed to return the same CSV.
Licence
The JMA's terms for the content of its web site (気象庁ホームページについて, コンテンツの利用について, https://www.jma.go.jp/jma/kishou/info/coment.html) follow the 公共データ利用規約 (第1.0版) (Public Data License 1.0), which is compatible with CC BY 4.0. This dataset is offered under CC BY 4.0, with the credit to the JMA and the statement that it was processed:
出典：気象庁ホームページ「過去の気象データ・ダウンロード」（https://www.data.jma.go.jp/risk/obsdl/index.php）を加工して作成
It is not an official product of the JMA.
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